Using plant sources but rare metal catalysts doesn’t get us very far.

The Earth has finite resources and they're not evenly distributed. As we use up the easy-to-access sources of ores and fossil fuels, some of the key foundations of modern society risk becoming rare and prohibitively expensive. Until we actually perfect fusion and asteroid mining, these are realities driving our push to develop sustainable practices.

At the meeting of the American Association for the Advancement of Science, researchers talked about the progress they're making when attempting to put industrial chemistry on a sustainable path. The overall belief of the panel is that it's not simply enough to make any one part of the process sustainable. Using a cheap and easily available catalyst to drive reactions that require fossil fuels will only buy us so much. It's only when we make every step of the process sustainable—including what happens to the chemicals when we're done with them—that we can really make progress.

The session's organizer, UCSB's Susannah Scott, set out the scale of the problem. Industrial chemistry needs account for something like a quarter of US energy use. The metals Ru, Te, Pd, Rh, Au, Pt, Re, Os, and Ir are all fantastic catalysts, but they are the least common elements in the crust relative to silicon. Princeton's Paul Chirik added a few more details: the current US lifestyle requires something like 80 different elements (GE, for example, uses 72 of the first 82 in the periodic chart). Right now, 19 of them come exclusively from different countries.

While supply is a challenge, disposal is a problem as well. Stephen Miller from the University of Florida said that, globally, we produce more than 200 billion kilograms of plastics each year. Very little of that gets recycled or will degrade naturally and this leaves us with a major disposal problem. The primary source of the raw materials used in these plastics is fossil fuels, and those are subject to the same sorts of price chaos that other energy uses have faced.

Sustainable carbon

So, how do we get around these challenges? Miller is working on making plastics sustainable on both the source and disposal sides of the equation. He said that, right now, the Earth's biomass incorporates carbon equal to 1,000 times the world's polymer production each year, but only five percent of the US' chemical production is currently using sustainable feed. The use of renewable carbon sources is expected to rise to 25 percent by 2030, and Miller's work may help get us there.

Right now, the big success story of bioplastics is poly-lactic acid, or PLA. It can easily be made from corn, has the right properties to be used in plastic shopping bags, and is, at least in theory, biodegradable. Unfortunately, to get it to degrade, you have to heat it and subject it to mechanical shredding. To get around this, Miller's group has introduced a second sustainable chemical to the polymerization, one that forms an acetal linkage (An O-C-O bond) to the polymer. Acetal bonds are present in cellulose, and Miller reasoned they should make the resulting polymer easier to break down. He found that it loses about two percent of its mass within 45 days, and it should be fully broken down within six years. This would clearly cut down on the waste problem.

His group is also taking advantage of a company that's figured out how to convert the lignin from plant matter (a complex polymer that helps provide strength to cellulose) into vanillin. The latter can be used as a building block for polymers that contain a branch with a benzene-like ring structure. That makes it similar to an existing polymer, PET, which is found in water bottles. After some tweaking of the chemistry involved, Miller's team has created something that has a higher glass transition temperature than PET, which would allow it to hold hot liquids. They're hoping to raise it even further to provide a material that could act as a replacement for polystyrene.

Cheap catalysts

Most of these reactions, whether sustainable or not, require catalysts that push the reaction forward, allowing them to proceed under milder conditions or ensuring that they produce the desired product. And, right now, catalysts typically mean rare earth metals, like the ones Scott listed in the introduction. Chirik's working on getting rid of them.

The advantage of these catalysts, he said, is two electrons that they can donate to the reactants, which are key for the interesting organic chemistry. The downside? Metals like platinum cost more than $10,000 per mole, and some inevitably gets lost in each reaction. But living systems catalyze interesting reactions using metals like iron, which only has one electron to donate—but only costs about $4 a mole. The trick, Chirik said, is that organisms complex the metals in an organic molecule that donates a second electron to iron (typically from a nitrogen atom), making it behave like it's a more expensive metal.

Shifting to iron-based catalysts (or those made with other cheap and abundant metals) has the potential to make industrial processes far more sustainable.

Chirik gave some specific examples of the reactions he'd like to fix. One of them involves breaking a carbon-carbon double bond to form a link to silicon, a reaction catalyzed by platinum. Each year, $350 million worth of platinum gets lost in the resulting polymer, which is used for things like the no-stick surface that you peel stamps and adhesive labels off. Chirik estimates that 30 to 40 percent of the cost of these labels comes from the platinum left behind in the backing. But his group has developed an iron-organic catalyst that is more active than platinum and doesn't produce unwanted side-products; it can also catalyze a wider range of reactions than platinum.

There was a similar story with low-rolling-resistance tires, where the existing platinum catalyst creates the right reaction product only 40 percent of the time. The iron-organic replacement gives a 95 percent yield, and it pushes the reaction forward without the need for any heat or the controlled addition of reactants. The work isn't limited to iron, either; Chirik's group is working with a drug company to develop a cobalt catalyst that produces a specific form of a chemotherapy drug.

The volumes needed and diversity of reactions used in industrial chemistry mean that this work is a good step towards sustainability, but it is only a start towards putting the field as a whole on a sustainable footing. And the chemical industries are inherently a bit conservative, as their end users have specific requirements for things like material properties and purity. Any new reactions will have to be validated and scaled up slowly. Still, the session made it clear that the barriers to sustainability don't lie in the chemistry itself, simply in finding the right chemistry to make the whole pathway—from source through catalyst to waste—green.

My question though is it near real use or 'five years out', what seems to be the default answer for far enough away that details on consumer/industrial release need not be asked for but not so far it seem like it will never happen. Also tends to still be five years out if followed up years later.

Stephen Miller from the University of Florida said that, globally, we produce more than 200 billion kilograms of plastics each year.

That seems widely underestimated, it would mean only 634 kg per year per person if this was for the U.S. only. I'm pretty sure we do consume as much, even produce is weighted in plastic bags, milk, juice, cans all have plastic lining, even cardboard boxes of dry pasta have a see-through sheet of plastic. And that's just for food. I am single and probably hoard several hundred kilograms of plastic in appliances alone, some more in shoes and clothes, in my car, my bike, and so on.

Using cheap catalysts, particularly iron, to produce fuels and commodity chemicals has been industrialized for decades (think WW2 Germany). What is rather interesting and left out of this article is the use of Gold and Platinum not to produce anything usable, but simply to characterize something made in lab or even biological (electron microscopes).

Not meaning to get political, but a lot of our problems with chemical disposal and reaching sustainability is not due to lack of knowledge, but out of date rules and regulations (think US Nuclear processing vs. France's Nuclear Processing). A Process Engineer at a Nuclear Facility once told me that the amount of nuclear waste we create here in the US that would fill a Olympic size swimming pool can be further processed in France (with their regulations) to fit inside a Coca-Cola bottle.

Now, what I think is most important to consider in regards to sustainable chemistry (given the stress on plastics throughout the article) isn't our limitations on scientific knowledge, but the capital costs associated with setting up/modifying industrial processes to become more sustainable. Don't get me wrong, engineers are hired all the time to work on this, but given how this country operates and allocates it's resources, simply put, this is just a very complex cost benefit analysis.

This is definitely a nice article, but in my opinion, it is incredibly misleading in regards to the real problem associated with sustainable chemistry and industrial processes.

re:" The trick, Chirik said, is that organisms complicate the metals in an organic molecule that donates a second electron to iron (typically from a nitrogen atom), making it behave like it's a more expensive metal."

I think the word was probably complex. I'm guessing you are yet another victim of auto-complete, (like me, for example, my moniker, which should have been veritas super omne "truth above all").

If we're talking about using catalysts similar or the same as those used in biological processes, could it be useful to look into growing and harvesting them from GMO bacteria? Or would it just be cheaper/easier to use straight chemistry to make big batches of them?

Fantastic possibilities here by the way. In my pre-professional days at college (some 35 yrs ago!) I found organic chem to be a fascinating study. The numerical modelling of reaction intermediates should allow for some very creative solutions to these resource limitation issues.

if we're going to make plastic out of corn, one thing that needs to be kept in focus is that corn requires alot of resources to cultivate. it isnt a very efficient crop. it also takes alot of land, which as our population grows, will be necessary for greater and greater food production. land competition with corn grown for plastics is likely to drive up food prices. examining these opportunity costs will be the real determination between efficient and non-efficient.

if we're going to make plastic out of corn, one thing that needs to be kept in focus is that corn requires alot of resources to cultivate. it isnt a very efficient crop. it also takes alot of land, which as our population grows, will be necessary for greater and greater food production. land competition with corn grown for plastics is likely to drive up food prices. examining these opportunity costs will be the real determination between efficient and non-efficient.

This. I'd argue corn itself is not sustainable, considering the amount of fossil fuel used to grow it. But the input/hectare is going down as yield goes up, so it's not unreasonable to imagine a future in which no fossil fuels are used for corn production. Especially if we can build a nitrogen fixing variety and no longer have to make as much fertilizer. Which would likely require a GMO. *gasp*

But first let's work on not burning a valuable resource like oil simply for its energy.

Not meaning to get political, but a lot of our problems with chemical disposal and reaching sustainability is not due to lack of knowledge, but out of date rules and regulations (think US Nuclear processing vs. France's Nuclear Processing). A Process Engineer at a Nuclear Facility once told me that the amount of nuclear waste we create here in the US that would fill a Olympic size swimming pool can be further processed in France (with their regulations) to fit inside a Coca-Cola bottle.

As a bit of clarification, official U.S. Uranium fuel policy is the "once-through' fuel cycle, the fear being that the Plutonium recovered in fuel reprocessing could be intercepted for illegitimate weapons use. This may change as it sinks in that even if commissioned, Yucca Mountain could not inter all the spent fuel from even our current inventory of Uranium power reactors, much less the increased nuke capability that will be required in the (hypothetical) case we actually wish to ameliorate global warming. In theory, advanced designs such as Integral Fast Reactor and various accelerator-driven sub-critical reactors could reduce the waste problem far beneath that which even the French have achieved.

Currently, plants in Europe are reprocessing spent fuel from utilities in Europe and Japan. Reprocessing of spent commercial-reactor nuclear fuel is currently not permitted in the United States due to the perceived danger of nuclear proliferation. However the recently announced Global Nuclear Energy Partnership would see the U.S. form an international partnership to see spent nuclear fuel reprocessed in a way that renders the plutonium in it usable for nuclear fuel but not for nuclear weapons...

As an alternative to the disposal of the PUREX raffinate in glass or Synroc, the most radiotoxic elements can be removed through advanced reprocessing. After separation the minor actinides and some long lived fission products can be converted to short-lived isotopes by either neutron or photon irradiation.

Its largely a matter of economics. Someday the U.S. will realize it will be a whole lot cheaper to just solve the power reactor waste problem than it is to continue our current ad-hoc storage policy. And politics, of course: it appears a majority of those who recognize the urgency of the looming global warming catastrophe still think their enemy is Uranium, rather than coal.

There was a conversation I had, with one of my professors last semester. He'd done is his doctoral thesis on renewable and sustainable resources.

In class one day he was relating the story of how at the beginning of the 80's environmentalists were arguing that prices for things like aluminum would skyrocket as our supply ran out over the course of the decade. And how an economist, being a bit of an asshole, predicted that just the opposite would happen, that prices wouldn't rise one bit. A decade late the economist was right, in fact prices for many of the commodities predicted to rise by the environmentalists actually fell over over the course of the decade.

Why? Because as the "easy" extraction areas ran out, we developed technology to lower the cost of extracting the "hard" to get ones. He then, oddly against his own point, later argued that we are running out of resources. To be that "asshole" economist once again, we won't run out.

COULD these renewable resource paths be the way forward? Yep, if they're cheaper than what we have now. Which is why I'm encouraged by the apparent goals of these. Sustainability is good, but to accomplish such it's actually going to have to be cost competitive. If it can't beat mining the sea floor, or going into space, then we're just going to end up going to the sea floor and space. Because for the vast majority, the environment be damned when it comes to that or their wallets.

Agreed on the need for replacement of inorganic catalyst but I can't help but feel like the 2nd half of the article was handwritten by Chirik as a promotional piece so he could get funds.

"Look at all the amazing things I've done! I've solved this problem! Give me more money"

Is everyone else asleep at the wheel? Why has nobody else done anything or is not mentioned? Working in industry, there's no way the hundreds of scientists there are not seeing the 40% cost and not doing something about it.

There was a conversation I had, with one of my professors last semester. He'd done is his doctoral thesis on renewable and sustainable resources.

In class one day he was relating the story of how at the beginning of the 80's environmentalists were arguing that prices for things like aluminum would skyrocket as our supply ran out over the course of the decade. And how an economist, being a bit of an asshole, predicted that just the opposite would happen, that prices wouldn't rise one bit. A decade late the economist was right, in fact prices for many of the commodities predicted to rise by the environmentalists actually fell over over the course of the decade.

Why? Because as the "easy" extraction areas ran out, we developed technology to lower the cost of extracting the "hard" to get ones. He then, oddly against his own point, later argued that we are running out of resources. To be that "asshole" economist once again, we won't run out.

COULD these renewable resource paths be the way forward? Yep, if they're cheaper than what we have now. Which is why I'm encouraged by the apparent goals of these. Sustainability is good, but to accomplish such it's actually going to have to be cost competitive. If it can't beat mining the sea floor, or going into space, then we're just going to end up going to the sea floor and space. Because for the vast majority, the environment be damned when it comes to that or their wallets.

You will run out eventually of easily available resources, there's absolutely no way to argue it. The question is not if but when. Technology can delay it but you're deluding yourself otherwise.

Thanks for another great article. I remember the topic being discussed briefly on stories about dwindling helium stocks.

I fear that these scarce catalysts, along with fossil fuels and water, will weigh heavily on the political history of this century. Already China has by far the largest supply of rare earth metals and has given signs that it intends to use this fact to its advantage, OPEC-style. Hopefully the discovery of new processes will allow us to shift our industry to more readily available raw materials.

In any case, I wonder what 7 billion people aspiring to middle class lifestyle (and the consumption associated with it) will do with regard to this. Even if we find more efficient processes based on more abundant resources, it will take a LOT of them to give those billions 2 cars per household, multiple cell phones, computers, tablets and whatnot. Not to mention the problem of dealing with their waste.

I see two paths: no change in consumption, and prices will simply go up due to increased demand and reduced supply (the degree of price increase will depend on alternative processes delaying the reduced supply); or we face the fact that we shouldn't buy into the excessive consumption sold by the people behind the permanent growth economy models, even if we *can* afford to consume at that level.

There was a conversation I had, with one of my professors last semester. He'd done is his doctoral thesis on renewable and sustainable resources.

In class one day he was relating the story of how at the beginning of the 80's environmentalists were arguing that prices for things like aluminum would skyrocket as our supply ran out over the course of the decade. And how an economist, being a bit of an asshole, predicted that just the opposite would happen, that prices wouldn't rise one bit. A decade late the economist was right, in fact prices for many of the commodities predicted to rise by the environmentalists actually fell over over the course of the decade.

Why? Because as the "easy" extraction areas ran out, we developed technology to lower the cost of extracting the "hard" to get ones. He then, oddly against his own point, later argued that we are running out of resources. To be that "asshole" economist once again, we won't run out.

COULD these renewable resource paths be the way forward? Yep, if they're cheaper than what we have now. Which is why I'm encouraged by the apparent goals of these. Sustainability is good, but to accomplish such it's actually going to have to be cost competitive. If it can't beat mining the sea floor, or going into space, then we're just going to end up going to the sea floor and space. Because for the vast majority, the environment be damned when it comes to that or their wallets.

You will run out eventually of easily available resources, there's absolutely no way to argue it. The question is not if but when. Technology can delay it but you're deluding yourself otherwise.

I'm not sure if this guy will run out of easily available resources. He seems like a bright dude and understands that economics drive the ability to use and obtain "resources." I'm not an English major, but I'm pretty sure one can always make an argument against someone when they don't specify the context involving their statement. This is the biggest problem with "sustainability," context. What does sustainability actually mean? We have devices in place to encourage sustainability, like recycling, but they do not work unless people utilize them. I could propose known chemical processes that are chemically sustainable in it's fullest, but what about energy? what about the economics of scale? Think about that a little.